1. Field of the Invention
The invention relates to a vehicle occupant protection device that protects an occupant of a vehicle with an airbag.
2. Description of Related Art
In an airbag device for a driver's seat described in Japanese Utility Model Application Publication No. 5-65706 (JP 5-65706 U), an airbag is divided into a plurality of chambers in at least a vehicle width direction. Also, an inflator has a gas generating chamber that is divided into a plurality of gas generating chambers corresponding to the plurality of chambers of the airbag, such that gas is able to be distributed to each of the chambers. Also, the plurality of gas generating chambers of the inflator are selectively activated so as to inflate the airbag in a suitable deployment pattern according to the circumstances of a collision. As a result, an occupant is more accurately protected.
On the other hand, in an airbag device for a front passenger's seat described in Japanese Patent Application Publication No. 2006-256508 (JP 2006-256508 A), an airbag is divided into three air chambers in the lateral direction by partition walls. Also, inflators that supply gas into the air chambers are provided one for each air chamber. When a frontal collision occurs, all of the air chambers are activated, but when an oblique collision occurs, the air chamber on the side opposite the collision is not inflated or inflated at a lower pressure. As a result, the air chamber on the collision side is inflated relatively more than the other air chambers, so occupant protection performance in the case of an oblique collision is improved.
When the configuration of a frontal collision is an asymmetric collision such as an oblique collision, a so-called small overlap collision or the like, the time during which the vehicle body deforms is longer and the acceleration generated in the vehicle body is smaller than they are when a symmetrical collision such as a full-lap collision occurs. As a result, when an asymmetric collision occurs, the rate of forward movement of the head of the occupant is slower and the time during which impact phenomena are occurring is longer than they are when a symmetrical collision occurs.